Oxide TFT Surface Protrusions for Grayscale and Switching Trade-off
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Solution Overview
Problem
The complexity and cost of manufacturing organic light emitting display devices are increased due to the need for different semiconductor materials and structures for driving and switching thin film transistors to achieve rich grayscale expression and fast switching, which complicates the process and elevates costs.
Innovation Solution
The organic light emitting display device employs a substrate with driving and switching thin film transistors, where the driving transistor includes a first oxide semiconductor layer with a surface treating layer of protrusions, and the switching transistor lacks this surface treating layer, allowing for differentiated electrical characteristics without the need for separate materials or structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different semiconductor materials and structures are used for driving and switching thin film transistors to achieve rich grayscale expression and fast switching, then grayscale expression and switching speed are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies local quality by forming a surface treating layer with protrusions only on the semiconductor layer of the driving thin film transistor, while the switching thin film transistor's semiconductor layer remains without such treatment. This localized differentiation modifies the S-factor specifically for the driving transistor to enhance grayscale expression, while keeping the switching transistor structure simple for fast switching, thereby resolving the contradiction between performance and manufacturing complexity
Solution Approach 2:
The patent changes the physical parameter of the semiconductor layer surface by introducing a surface treating layer with protrusions. This structural modification alters the electrical characteristics and S-factor of the driving thin film transistor, enabling rich grayscale expression without changing the semiconductor material type or overall device structure, thus avoiding increased manufacturing complexity
2Reliability
If different semiconductor materials and structures are used for driving and switching thin film transistors, then electrical characteristics are optimized for different functions, but manufacturing cost increases
Solution Approach 1:
The patent implements local quality by applying the surface treating layer with protrusions only to the driving thin film transistor's semiconductor layer, while the switching thin film transistor remains untreated. This selective treatment optimizes electrical characteristics for each transistor's specific function without requiring different semiconductor materials, thereby avoiding increased manufacturing cost while achieving differentiated performance
Solution Approach 2:
The patent uses the same oxide semiconductor material for both driving and switching thin film transistors, making the semiconductor layer universally applicable to both device types. The functional differentiation is achieved not through material variation but through selective surface treatment, reducing manufacturing cost by eliminating the need for multiple semiconductor material deposition processes
Data Source
AI summary
An organic light emitting display device comprises a substrate including a display area and a non-display area, a driving thin film transistor and at least one switching thin film transistor in the display area, and an organic light device in the display area, wherein the driving thin film transistor and the switching thin film transistor include respectively an oxide semiconductor layer, and wherein a surface treating layer including a pattern of protrusions is on an upper surface of the oxide semiconductor layer of the driving thin film transistor.